定时器(OS)

最新推荐文章于 2025-01-14 21:25:23 发布

原创最新推荐文章于 2025-01-14 21:25:23 发布 · 235 阅读

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CC 4.0 BY-SA版权

文章标签：

#timer #os #struct #module #class #file

本文介绍了基于三星s3c2410 CPU的开发板上，如何在Linux操作系统下利用定时器0产生中断，实现LED灯闪烁的功能。实验通过平台设备驱动机制，将硬件资源与驱动分离，提高代码可移植性。程序执行后，终端显示信息且LED灯D12闪烁。驱动程序分为timer0_dev.c和timer0_drv.c两个部分。

一、实验平台：开发板fs2410，采用三星s3c2410的CPU，linux操作系统。

二、实现功能：主程序打印提示信息(当然可以做你想做的事)，用定时器0产生中断，是LED灯D12闪烁。

三、实验原理：

这里采用平台设备驱动机制，将硬件资源与驱动分开，提高了代码的可移植性。

四、实验现象：

应用程序执行后，主程序在终端打印信息，D12在闪烁。

五、实验总结：

使用平台设备驱动机制，整个驱动程序分成了几个部分，本例中是timer0_dev.c和timer0_drv.c

六、示例代码：

驱动部分：

/*timer0_dev.c*/
#include<linux/kernel.h>
#include<linux/module.h>
#include<linux/init.h>
#include<linux/device.h>
#include<linux/fs.h>
#include<linux/platform_device.h>
#include <asm/mach/map.h>

static struct resource timer0_resource[] = {
	[0] = {
		.start = S3C24XX_PA_TIMER,
		.end   = S3C24XX_PA_TIMER + 0xff,
		.flags = IORESOURCE_MEM,
	},
	[1] = {
		.start = IRQ_TIMER0,
		.end   = IRQ_TIMER0,
		.flags = IORESOURCE_IRQ,
	}
};

void timer0_release(struct device * dev)
{
	
}

struct platform_device timer0_device = {
	.name	  = "timer0",
	.id		  = -1,
	.num_resources	  = ARRAY_SIZE(timer0_resource),
	.resource	  = timer0_resource,
	.dev		={
		.release 	=timer0_release,
	},
};

int __init timer0_dev_init(void)
{
	platform_device_register(&timer0_device);
	
	return 0;
}

void __exit timer0_dev_exit(void)
{
	platform_device_unregister(&timer0_device);
}

module_init(timer0_dev_init);
module_exit(timer0_dev_exit);

MODULE_LICENSE("GPL");

/*timer0_drv.c*/
#include<linux/kernel.h>
#include<linux/device.h>
#include<linux/fs.h>
#include<linux/init.h>
#include<asm/io.h>
#include<asm/irq.h>
#include<asm/uaccess.h>
#include<linux/interrupt.h>
#include<asm/arch/regs-gpio.h>
#include<asm/arch/leds-gpio.h>
#include<linux/platform_device.h>

int count = 0;
static unsigned int timer0_major = 0;
static struct class *timer0_class = NULL;
struct resource *res;

struct s3c2410_timer{
	volatile unsigned long tcfg0;
	volatile unsigned long tcfg1;
	volatile unsigned long tcon;
	volatile unsigned long tcntb0;
	volatile unsigned long tcmpb0;
};

struct s3c2410_timer *timer0;

static irqreturn_t timer0_irq(int irq, void *dev_id)
{
	if(count%2 == 0)
		s3c2410_gpio_setpin(S3C2410_GPF4, 0);
	else
		s3c2410_gpio_setpin(S3C2410_GPF4, 1);

	count++;

	return IRQ_HANDLED;
}

static int timer0_open(struct inode *inode, struct file *file)
{
	int ret;
	s3c2410_gpio_cfgpin(S3C2410_GPF4, S3C2410_GPF4_OUTP);
	s3c2410_gpio_setpin(S3C2410_GPF4, 1);
	
	timer0->tcfg0 = 249;  //预分频器
	timer0->tcfg1 = 2;  //多路开关设为1/8
	timer0->tcntb0 = 12500;  //输出方波的周期为1s
	timer0->tcon |= 0xb;
	timer0->tcon &= ~(1<<1);

	ret = request_irq(res->start, timer0_irq, 0, "timer0", "a");
	
	return 0;
}

static int timer0_close(struct inode *inode, struct file *file)
{
	free_irq(res->start, "a");

	return 0;
}

struct file_operations timer0_fops = {
	.owner 	= THIS_MODULE,
	.open 	= timer0_open,
	.release 	= timer0_close,
};

static int __devinit timer0_probe(struct platform_device *pdev)
{

	/*获得I/O资源*/
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	/*映射*/
	timer0 = (struct s3c2410_timer *)ioremap(res->start, res->end-res->start+1);

	/*获得中断资源*/
	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);

	/*注册*/
	timer0_major = register_chrdev(0, "timer0", &timer0_fops);
	timer0_class = class_create(THIS_MODULE, "timer0_class");
	class_device_create(timer0_class, NULL, MKDEV(timer0_major,0), NULL, "timer0");
	
	return 0;
}

static int __devexit timer0_remove(struct platform_device *pdev)
{
	unregister_chrdev(timer0_major, "timer0");
	class_destroy(timer0_class);
	class_device_destroy(timer0_class, MKDEV(timer0_major,0));

	iounmap(timer0);
	
	return 0;
}

struct platform_driver timer0_driver = {
	.probe 	= timer0_probe,
	.remove 	= timer0_remove,
	.driver 	= {
		.owner 	= THIS_MODULE,
		.name 	= "timer0",
	},
};
int __init timer0_init(void)
{
	platform_driver_register(&timer0_driver);
	
	return 0;
}

void __exit timer0_exit(void)
{
	platform_driver_unregister(&timer0_driver);
}

module_init(timer0_init);
module_exit(timer0_exit);

MODULE_LICENSE("GPL");

/*测试代码timer0_test.c*/
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>

int main(void)
{
	int fd;
	if((fd = open("/dev/timer0",O_RDWR)) == -1){
		perror("open /dev/timer0 failed");
		exit(-1);
	}

	while(1){
		printf("main process...\n");
		sleep(1);
	}

	return 0;
}